A Nexus spokesman said: “We had planned ahead for the introduction of the new note but that work could not start until the new note actually came out on September 13 as we needed a whole batch of them to start testing them each of the ticket machines and running the appropriate software changes.

“The upgrade that was required is now ready to roll out so that all 225 of our ticket machines will take the new polymer bank notes by the end of this week.

“In the meantime customers can still pay for their travel with other bank notes, coins, and credit and debit cards.”

After the Chronicle contacted Metro to report our findings they themselves tested out one of their machines and sent us a video of it working, which you can see below. But it won't be until the end of this week that they say all machines will have the successful software update.

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The new five pound notes, which are made of durable polymer which gives them a plastic feel, will completely replace the old paper notes by May 2017, when the old money will cease to be legal tender.

In summer 2017 a ‘plastic’ £10 will also be rolled out, followed by £20 by 2020.